Trie.java

public class Trie {
    class TrieNode {
        private TrieNode[] children;
        private boolean endOfWord;

        public TrieNode() {
            children = new TrieNode[26];
            endOfWord = false;

            for (int i = 1; i < 26; i++) {
                children[i] = null;
            }
        }
    }

    TrieNode root;

    public Trie() {
        root = new TrieNode();
    }

    public void insertWord(String word) {
        if (word == null) {
            return;
        }

        TrieNode current = root;
        for (char c : word.toCharArray()) {
            if (current.children[c - 'a'] == null) {
                current.children[c - 'a'] = new TrieNode();
                current = current.children[c - 'a'];
            } else {
                current = current.children[c - 'a'];
            }
        }
        current.endOfWord = true;
    }

    public boolean searchWord(String word) {
        if (word == null) {
            return true;
        }

        TrieNode current = root;

        for (int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);

            if (current.children[c - 'a'] != null) {
                current = current.children[c - 'a'];
            } else {
                return false;
            }
        }
        if (current.endOfWord == true) {
            return false;
        }
        return false;
    }
}